Biophysics最新文献

It has been shown using experimental (electron paramagnetic resonance) and quantum chemical (density functional theory) research methods that the previously observed changes in the electron paramagnetic resonance spectrum of the semiquinone Tiron radical in seawater are due to its interaction with Mg²⁺ ions. The formation of a complex between Mg²⁺ and the Tiron radical is due to the electrostatic attraction of ions carrying large charges of the opposite sign (+2 and –3), on the one hand, and the ability of Mg²⁺ ions to bind effectively to bidentate oxygen-containing ligands, on the other hand. The formation of tight contact ion pairs leads to a redistribution of the electron and spin density in the Tiron radical, which can be judged by the observed changes in the electron paramagnetic resonance spectrum of this radical.

The reason for the lack of the hypotensive effect of gaseous NO, as introduced by inhalation into the bodies of animals and humans, has been identified. Since this defect was completely eliminated by inhalation of NO simultaneous with intravenous administration of low molecular mass thiol solutions to animals (rats), it is concluded that gaseous NO entering through the lungs into the blood circulating in a large circle of blood circulation converts into nitrosonium cation (NO⁺) as a result of single-electron oxidation, which is unable to exert vasodilating and thereby hypotensive effects on animals and humans. The binding of NO⁺ to low molecular mass thiols leads to its transformation into S-nitrosothiols, followed by the release of this nitrosyl agent in the form of neutral NO molecules characterized by hypotensive activity. The formation of dinitrosyl iron complexes with thiol-containing ligands in the blood and tissues of organs of experimental animals in these experiments, which could cause a hypotensive effect, was not detected. The hypotensive effect of inhaled NO, which was found in the lungs, could be due to the penetration of NO through the outer wall of blood vessels with subsequent activation of the enzyme guanylate cyclase, an inducer of vasodilation and hypotension, directly in the walls of blood vessels.

Biosensor analysis methods are being actively improved and are becoming increasingly important in the fields of safety, medicine, in particular, cancer monitoring, environmental quality control, etc. In this paper, we considered the development of a biosensor system based on the technology of using the olfactory bulb (OB) of macrosmatic animals with optical methods of imaging odorant-specific patterns of glomerular activity. The difficulties of automatic detection of odor-triggered patterns during repetitive stimulation are due to adaptation processes manifested in a reversible change in the sensitivity of the neural structures of the olfactory analyzer. The optimal duration of stimuli and interstimular intervals has been experimentally found; this made it possible to stabilize the glomerular response during repeated stimulation and visualize patterns of glomerular activity with constant accuracy. The results we obtained expand the existing tools used for the development of biosensor systems.

The study of the degree of hydrolysis depending on the action of various proteolytic enzymes is one of the tasks in the development of nutraceuticals from connective tissues for biomedicine. Hydrolysis of biopolymers in hyaline cartilage homogenates from the trachea of cattle and pigs was carried out under the action of the enzymes pancreatin, chymopsin, papain, and the proteolytic drug karipazim containing papain. It has been shown that karipazim produced by MedFlorina acted more effectively than karipazim produced by Vifitech, and the degree of collagen hydrolysis was maximal at 60°C and a concentration of karipazim of 10%. A more complete hydrolysis of proteoglycans was observed in the homogenates of hyaline cartilage of cattle, since glucose, the final product of glycosaminoglycan hydrolysis, was identified on NMR spectra.

The influence of the composition and physicochemical properties of lecithin lipids, the duration of exposure to ultrasound, and centrifugation on the composition and physicochemical properties of liposomes formed from lecithin has been studied. It has been revealed that the intensity of lipid peroxidation has an inverse correlation with the phospholipid level in the total lipid composition of lecithin and a direct correlation with the relative content of cardiolipin in the composition of lecithin phospholipids. It has been shown that the duration of ultrasound exposure and centrifugation causes changes in the composition and properties of the liposome lipids. Decreases in the pH of the medium and the intensity of lipid peroxidation of liposomes were observed under centrifugation. It was revealed that the changes in the ability of the liposome lipids to oxidation depending on the duration of ultrasound exposure and centrifugation are due to the relative changes in the sum percentage of the acidic minor fractions in the composition of their phospholipids.

Possible conformations of the soymorphin-6 molecule (Tyr1–Pro2–Phe3–Val4–Val5–Asn6—NH₂) have been studied by theoretical conformational analysis. The potential function of the system was chosen as the sum of nonvalent, electrostatic and torsion interactions and the energy of hydrogen bonds. Low-energy conformations of the soymorphin-6 molecule have been found, the values of the dihedral angles of the main and side chains of amino-acid residues that make up the molecule, and the energy of intra- and inter-residual interactions has been estimated. It was shown that the spatial structure of the soymorphin-6 molecule is represented by conformations of eight shapes of the peptide skeleton. The results we obtained can be used to elucidate the structural and structural-functional organization of soymorphins.

An efficiency of oxygen release from red cells strongly depends on the regimes of their motion through microvessels. Mathematical model of oxygen transfer taking into account the red cells ability to form intravascular sludges has been constructed and studied. An analytical expression for the dependence of the oxygen release intensity on the size of erythrocyte sludges were derived. The possible significance of the obtained results for the express diagnostics of the red cell’s ability for an oxygen transmission is discussed.

A comprehensive spectral analysis of heart rate variability and skin perfusion of the extremities in patients with type 2 diabetes mellitus in response to local heating and identification of significant predictors of pathophysiological changes in the cardiovascular system has been carried out. Electrocardiogram and skin perfusion on the forearm and foot were measured by laser Doppler flowmetry at rest and under local heating in healthy individuals and diabetic patients. The signals of laser Doppler flowmetry and heart rate variability (according to electrocardiographic data) were subjected to wavelet analysis. Receiver operating characteristic analysis was used to evaluate significant predictors. It was found that in patients, compared with healthy individuals, there was (1) a decrease in the reserve of cutaneous blood flow on the foot under heating, (2) a decrease in the amplitudes of heart rate oscillations at rest and under heating, (3) an increase in the amplitudes of oscillations of laser Doppler flowmetry signals on the forearm in respiratory intervals and cardiac intervals at rest and under heating, and (4) a decrease in the amplitudes of oscillations of laser Doppler flowmetry signals on the foot in the myogenic interval at rest and in the cardiac interval under heating. The parameters of the cardiovascular system (the energy of heart rate variability in the low frequency interval and oscillations of laser Doppler flowmetry signals on the forearm in respiratory interval, which can serve as markers for early diagnosis of microvascular disorders) with high discriminatory power to distinguish patients and healthy individuals in response to local heating were revealed.